Naso-gastric feeding tubes, also known as enteral feeding tubes or enteric feeding tubes, are typically used to introduce nutritional substances or other prescribed products to a patient. The products are typically in a "soupy" form of liquid and solid or liquid only.
The tubes usually have a weighted distal end called a bolus, which is used to assist in placing the tube within the patient and for keeping the tube in that position once it is correctly positioned.
The proximal end of the naso-gastric tube is typically connected to an enteral administration set which in turn is connected to a container having a prescribed product therein. Such an enteral feeding container and enteral administration set are shown for example in U.S. Pat. No. 4,335,770 to Kulle et al., assigned to the assignee of the present invention. The nutrition product is then delivered to the patient through the administration set and the feeding tube.
A principal problem associated with naso-gastric feeding tubes is their proper placement within the patient. It is advantageous for the feeding tube to be quite flexible so as to cause less pain and trauma to the patient and to increase the period of time of possible intubation. To enable insertion of the extremely flexible feeding tube through the nose and down into the stomach or intestine of the patient, the tube must be made more rigid. To allow for placement of this flexible tube, a rigid wire stylet or other structure is usually employed and is removably mounted within the hollow tube, allowing the tube to be flexible but providing sufficient rigidity to insert the feeding tube into the patient. Other means for increasing the rigidity of the feeding tube are also known. The wire stylet is removed before delivery of the prescribed product so that the feeding tube will be extremely flexible for the remainder of the time it is within the patient.
One way to confirm proper placement of the distal end of the feeding tube is to take an x-ray of the tube while the stylet is still in place. This is a relatively time-consuming and expensive placement confirmation procedure and exposes the patient to x-rays. However, it has the advantage that, should placement be improper, the stylet and feeding tube may be moved together within the patient until placement is correct.
Two other more commonly used means to test for the proper positioning of the tube both require removal of the stylet after the operator believes insertion of the tube is proper. Once the stylet is withdrawn, the first procedure requires connecting a syringe to the proximal end of the feeding tube. The operator then pulls the piston to expand the syringe cylinder, attempting to withdraw some liquid from the stomach into the syringe. If liquid from the stomach is withdrawn, the operator knows that proper placement has been achieved. Alternatively, in the second procedure, once the stylet is removed, the operator secures a syringe to the proximal end of the feeding tube, as with the first procedure. The operator then forces air or other fluid out of the syringe, through the feeding tube and listens with a stethoscope for gurgling or other audible mark in the patient's stomach. Occurrence of the audible mark confirms proper tube placement.
The disadvantage with each of these two procedures is that removal of the stylet is required. If proper placement is confirmed by the test procedure, no problem is presented and the feeding tube may be connected to a source container of a prescribed product, usually by means of the above-mentioned administration set. However, the first attempt at proper feeding tube placement is often unsuccessful, which usually requires that the stylet be reinserted into the feeding tube. This is often painful to the patient and is a time consuming procedure as well. When the stylet is reinserted, the operator attempts to re-position the feeding tube. The operator then withdraws the stylet once more and performs one of the placement confirmation tests with the syringe as described above. This procedure is repeated until proper placement is confirmed.
Another problem associated with providing prescribed substances such as nutrition products to a patient through an enteral system is that the systems do not provide for the immediate addition of a second prescribed product. A second prescribed product, such as for example a drug or vitamins, may be added to the source container, such as the container shown in the above-identified U.S. Pat. No. 4,335,770. However, this means the second prescribed product will be diluted within the entire amount remaining of the first prescribed product. Furthermore, the second prescribed product will be delivered over a rather lengthy time period. The second prescribed product cannot be delivered immediately unless the feeding tube is disconnected from the source container and the second prescribed product delivered by syringe, for example, at the proximal end of the feeding tube. U.S. Pat. No. 4,388,076 discloses an intubating device with a hollow stylet plug through which fluid may pass to confirm proper tube placement while the stylet is still within the tube. However, such a structure suffers from the deficiencies of other feeding tubes in that the addition of a second prescribed product quickly and without dilution by the first prescribed product requires that the feeding tube be disconnected from the administration set and reconnected after injection of the second prescribed product. In addition, even if the operator goes to this trouble to introduce a second product, the second product cannot be delivered over an extended time period, separately from the first product.
It is apparent that there is a great need for a naso-gastric feeding tube which reduces insertion time and trauma to the patient and which allows for subsequent delivery of a second prescribed product without disconnecting the delivery system.